What this calculator does
Find out how much of the yeast you have equals the yeast your recipe asks for. Bread recipes call for one of three kinds of yeast. The one in your cupboard is often not the one on the page. Active dry yeast, instant yeast and fresh (cake or compressed) yeast all raise dough. But each holds a different amount of living yeast per gram, so they don't swap one for one. This converter changes the amount so your dough gets the same rising power.
It uses the ratio most bakers work with. Instant yeast is the strongest by weight, and active dry needs about 25% more. Fresh yeast needs about three times the weight of instant. Enter the amount in grams, ounces, level teaspoons or 1/4 oz packets. The answer comes back in grams and ounces. If the yeast you have is dry, you also get teaspoons and packets.
Where it's used
Why this math matters outside the classroom:
- Bread baking. A baker with only instant yeast replaces 10 g of active dry yeast with 10 × 0.8 = 8 g of instant.
- Ratio reasoning. Students use the ratio 3 : 1 to find that 12 g of instant yeast matches 36 g of fresh yeast.
- Unit conversion. Since a 7 g packet is 2 1/4 tsp, 2 packets of yeast are 14 g or 4 1/2 teaspoons.
- Bakery scaling. A bakery switching 1 kg of fresh yeast to instant orders about 333 g, a third of the weight.
- Old recipes. A family recipe calling for one 0.6 oz yeast cake works with one 1/4 oz packet of active dry yeast.
Grade level and standards: Grade 6; Common Core State Standards for Mathematics 6.RP.A.3, 6.RP.A.3.d. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
How to use it
- Choose the yeast the recipe asks for.
- Enter the amount and its unit: grams, ounces, teaspoons or packets. Fresh yeast must be entered by weight.
- Choose the yeast you have.
- Use the converted amount. For dry yeast, the teaspoon result also shows the nearest measuring-spoon size.
What the inputs mean
- Yeast in the recipe
- Active dry yeast has larger grains and is often dissolved in warm water first. Instant yeast (also sold as rapid-rise or bread machine yeast) has finer grains. You can mix it straight into the flour. Fresh yeast is a moist, crumbly block sold chilled.
- Amount in the recipe
- A US packet of dry yeast holds 1/4 oz (7 g), about 2 1/4 level teaspoons. Teaspoons are converted at 7 g ÷ 2.25, about 3.11 g each.
Formula and method
relative weight for the same rise: instant 1, active dry 1.25, fresh 3 new amount = recipe amount × (weight of new type ÷ weight of recipe type) 1 packet = 7 g = 2 1/4 tsp, so 1 tsp of dry yeast ≈ 3.11 g 1 oz = 28.349523125 g
Each yeast gets a relative weight: how much of it gives the same rise as 1 gram of instant. To swap, the calculator first turns the recipe's amount into grams. Then it multiplies by the new type's weight divided by the recipe type's weight. Going from active dry to instant multiplies by 1 ÷ 1.25 = 0.8. Going from instant to fresh multiplies by 3.
These ratios match a swap bakers have used for years. One 0.6 oz cake of fresh yeast replaces one 1/4 oz packet of active dry: 0.6 × 1.25 ÷ 3 = 0.25 oz. They're a custom rather than an exact law, because yeast strength varies with brand, age and storage.
Worked example
A recipe asks for 1 packet of active dry yeast, and you have instant yeast.
- 1 packet = 7 g of active dry yeast.
- Instant yeast needs 1 ÷ 1.25 = 0.8 of that weight: 7 × 0.8 = 5.6 g.
- In teaspoons: 5.6 ÷ 3.11 = 1.8 tsp, about 1 3/4 tsp.
Result: Use 5.6 g of instant yeast, about 1 3/4 level teaspoons or 0.8 of a packet.
Understanding the result
Yeast amounts don't need to be exact. A little more speeds the rise, and a little less slows it. So judge the dough by how it looks (roughly doubled) rather than by the clock.
When you switch from active dry to instant yeast, you can usually skip proofing it (soaking it in warm water first). Add the water to the dough instead.
Assumptions and limitations
- The yeast is fresh and has been stored as its package directs.
- Teaspoons are level and the packet is the 1/4 oz (7 g) US size.
- The relative strengths are 1 : 1.25 : 3 for instant, active dry and fresh.
- Brands and batches differ, and some bakers swap active dry and instant one for one. Expect to adjust rising times, rather than the amount.
- Fresh yeast can't be measured by the spoon. Its block sizes also vary by country (0.6 oz, 2 oz, 42 g and others), so weigh it.
- Sourdough starter isn't a yeast type this converter handles.
Frequently asked questions
Can I use instant yeast instead of active dry yeast?
Yes. Use about 20% less by weight (multiply by 0.8), and mix it straight into the dry ingredients. Many home bakers swap them one for one. The dough will just rise a little faster.
How much dry yeast replaces fresh yeast?
Use about 40% of the fresh weight in active dry yeast, or about a third of it in instant yeast. 30 g of fresh yeast becomes about 12.5 g of active dry or 10 g of instant.
How many teaspoons are in a packet of yeast?
A US 1/4 oz (7 g) packet holds about 2 1/4 level teaspoons of dry yeast.
Why does my converted dough rise at a different speed?
Rising speed depends on more than the amount. Dough temperature, sugar, salt and the yeast's age all play a part. Let the dough, not the timer, tell you when it's ready.
How this calculator is checked
Method: Common baker's conversion of yeast types by weight (instant 1 : active dry 1.25 : fresh 3), consistent with the traditional 0.6 oz fresh cake = 1/4 oz active dry packet swap; US packet of 1/4 oz (7 g) ≈ 2 1/4 tsp. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.
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